When work is being done in a site exposed to ionizing radiation, particularly for the purpose of maintenance, security or dismantling, a person or object subjected to said radiation is monitored by means of an individual detector, such as a dosimeter, to determine the quantity of radiation received. Besides, automatic measuring devices or beacons are used to collect data and obtain a map of the intensity of exposure on the site. The information is particularly used to organize and plan the work, particularly shift rotation, the number of persons, the resources required and the time for carrying out a job depending on the resources available and the risks to which the resources are exposed, on the basis of relevant physiological, technical and legislative data.
Before any work on a site subjected to ionizing radiation, a provisional dosimetry evaluation is carried out from readings taken in the working area by radiation protection technicians, such as dose rate measurements and contamination measurements. These measurements are copied to a map, known as the initial map. Then, at each stage of the work during which the conditions of exposure could be modified, a map is prepared once again. The making of such an updated map involves stopping the work and bringing radiation protection technicians back on the site to take the measurements once again.
All site workers are equipped with a dosimeter that makes it possible to measure the quantity of radiation received. The open working time of each person is calculated theoretically, from the map and their area of work, based on a provisional dosimetry evaluation, and corrected if needed from the data relating to the dose effectively received by the person, obtained from their dosimeter. That actual exposure is observed after the event. Thus, this method of planning of the prior art does not make it possible to make optimum use of the resources in respect of the exposure and the dose received by them. The uncertainty about the actual exposure makes it necessary to apply a safety margin in view of standards.
Document U.S. Pat. No. 5,572,027 describes a dosimeter that combines a dosimeter known as an active dosimeter, adapted to measure a dose rate, and a dosimeter known as a passive dosimeter, adapted to measure a quantity of radiation received.
Document U.S. 2012 0154170 describes an individual dosimeter adapted to communicate in real time with a supervision station and thus determine the radiation dose received by the wearer of said dosimeter.
Document EP 0 542 561 describes a measuring device that can measure the radiation intensity values in an environment and superimpose them on an image of said environment so as to inform an operator of the exposure risks.
These devices of the prior art allow the passive supervision of the exposure of resources. The supervision is known as passive because it does not allow real time monitoring or control of the dose received by the person, particularly as a function of the variation of the dose rate to which they are subjected in view of their location in the working zone. Now, operators are limited in terms of the total dose received over a long period, for example over a year, in the case of exposure to ionizing radiation. Thus, with the supervision devices of the prior art, it is possible for an operator to be unnecessarily exposed in view of their location and task, while moving said operator by a few meters would be enough to save the potential of the resource.